Many semiconductor imaging sensors today are front side illuminated. That is, they include imaging arrays that are fabricated on the front side of a semiconductor wafer, where light is received at the imaging array from the same front side. The electrical contacts for the imaging arrays are also fabricated on the front side of the wafer. Thus, the electrical contacts for these front side illuminated devices are typically routed out through the side for connecting to bump pads or other bonding elements on the back side of the sensor.
For example, FIGS. 1A-1E illustrate cross-sectional views of a prior art imaging sensor 100 and a method of making the same. Imaging sensor 100 is illustrated as including a semiconductor wafer 102 and a light transparent later 104. In FIG. 1A, imaging array 106, metal pads 108 and multiple seal rings 110 are formed on the front side of wafer 102. A glass cover 112 may then be affixed to the front side of wafer 102. The back side of wafer 102 is then ground down in FIG. 1B. In FIG. 1C, wafer 102 is then cut through metal pads 108 in order to access the sidewall of sensor 100. FIG. 1D illustrates the forming of metal connections 114 on the sidewall and back side of sensor 100 in order to distribute the connections of imaging array 106 along the back side of sensor 100. Finally, in FIG. 1E, bump pads 118 are formed on the backside of sensor 100 in order to provide a bonding area for the sensor.